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<front>
<journal-meta>
<journal-id journal-id-type="archive">gsminmag</journal-id>
<journal-title>Mineralogical Magazine</journal-title>
<abbrev-journal-title abbrev-type="full">Mineralogical Magazine</abbrev-journal-title>
<issn pub-type="ppub">0026-461X</issn>
<publisher>
<publisher-name>Mineralogical Society</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.1180/minmag.1993.057.389.01</article-id>
<title-group>
<article-title>The Origins of Contrasting Zoning Patterns in Hyalophane from Olivine Leucitites, Northeast China</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Zhang</surname>
<given-names>Ming</given-names>
</name>
<xref ref-type="author-notes" rid="FN1">*</xref>
<aff>Department of Geology, Imperial College, London SW7 2BP, U.K., and Department of Geological Sciences, Southern Methodist University, Dallas, TX 75275, U.S.A.</aff></contrib>
<contrib contrib-type="author">
<name>
<surname>Suddaby</surname>
<given-names>Paul</given-names>
</name>
<aff>Department of Geology, Imperial College, London SW7 2BP, U.K.</aff></contrib>
<contrib contrib-type="author">
<name>
<surname>Thompson</surname>
<given-names>Robert N.</given-names>
</name>
<aff>Department of Geological Sciences, University of Durham, Durham DH1 3LE, U.K.</aff></contrib>
<contrib contrib-type="author">
<name>
<surname>Dungan</surname>
<given-names>Michael A.</given-names>
</name>
<aff>Department of Geological Sciences, Southern Methodist University, Dallas, TX 75275, U.S.A.</aff></contrib></contrib-group>
<author-notes>
<fn fn-type="present-address" id="FN1"><label>*</label><p>Present address: School of Earth Sciences, Macquarie University, NSW 2102, Australia</p></fn></author-notes>
<pub-date pub-type="ppub">
<month>12</month>
<year>1993</year>
</pub-date>
<volume>57</volume>
<issue>389</issue>
<fpage>565</fpage>
<lpage>573</lpage>
<history>
<date date-type="received">
<day>25</day>
<month>8</month>
<year>1992</year>
</date>
<date date-type="rev-recd">
<day>18</day>
<month>11</month>
<year>1992</year>
</date></history>
<copyright-statement>Copyright &#x00A9; 1993, The Mineralogical Society</copyright-statement>
<copyright-year>1993</copyright-year>
<abstract>
<title>Abstract</title>
<p>Olivine (ol) leucitite lavas from Northeast China contain hyalophanes with contrasting Ba-zoning patterns. The hyalophanes occur: (1) in a magmatic inclusion (DZ2n), consisting of barian-titanian phlogopite + hyalophane + leucite + sodalite, and (2) as a mantle surrounding a sanidine megacryst (DZ19). Hyalophanes contain 4.6-20.2 mol.% celsian (Cn). The DZ2n hyalophane is normally zoned with respect to Ba (decreasing Ba toward rim), whereas the hyalophane mantle of megacryst DZ19 is reversely zoned. DZ2n probably crystallised from an extensively evolved (&#x003E;80 wt.% crystallisation) potassic melt derived from a primitive magma chemically similar to the host, at relatively low temperatures and pressures (e.g. <italic>T</italic>&#x223C;720&#x00B0;C <italic>P</italic>&#x223C;2 kbar). Competition with barian-titanian phlogopite for Ba, and limited Ba supply from the residual melt are the main cause for the normal Ba zonation. Sanidine megacryst DZ19 originated as a high <italic>P-T</italic> product (e.g. <italic>T</italic> &#x003E;950 &#x00B0;C, <italic>P</italic> &#x003E; 15 kbar) of an evolved leucite (lc) basanite/trachybasalt genetically related to ol-leucitites. Subsequently, it was incorporated into the host ol-leucititic magma at which point it was partially resorbed and then mantled by hyalophane. An increase in <italic>K</italic><sub>Ba</sub><sup>af/liq</sup> values with decreasing temperature and pressure and co-crystallisation of the hyalophane mantle with Ba-free phases may have caused the unusual reverse zonation</p></abstract>
<kwd-group>
<title>Keywords</title>
<kwd>zoning</kwd>
<kwd>hyalophane</kwd>
<kwd>leucitites</kwd>
<kwd>China</kwd>
<kwd>olivine</kwd>
</kwd-group>
</article-meta>
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